Parity and wind impact on the frequency of Anopheles marajoara in Brazil

Abstract

OBJECTIVE: To evaluate the impact of wind velocity on the behavior of An. marajoara population and its parity. METHODS: Collections were made bimonthly from January 1999 to February 2000 in the municipality of Ilha Comprida, Brazil. Adult mosquitoes were captured with a battery hand aspirator. Mann-Whitney test was applied to verify the wind impact on mosquito behavior. Polovodova technique and Christophers and Mer's follicular development analysis were used to determine parity. RESULTS: A total of 11,833 mosquitoes were captured, including 3,072 An. marajoara specimens. The peak of activity of An. marajoara occurred from 2 to 5 AM. Amongst 1,006 An. marajoara females who had their ovarioles dissected, it was found 530 (52.7%) nulliparous, 432 (42.9%) uniparous, 24 (2.4%) biparous and 1 multiparous. According to Christophers and Mer analysis, 982 (97.6%) had their follicles in phases I and II, 7 in phases III and IV, and 17 in phase V. The frequency of An. marajoara was significantly lower when wind velocity was 3 km/h or more or below 3 km/h. CONCLUSIONS: An. marajoara mosquitoes were more active at night. About 50% of dissected An. marajoara females were oniparous. Another important finding was the high proportion of females (97.6%) with follicles in the Christophers and Mer's phases I and II, suggesting the presence of gonotrophic concordance. Wind velocity equal or higher than 3 km/h considerably reduced the frequency of An. marajoara.